The invention relates to a process a for producing a ceramic-metal substrate.
Processes for producing metal-ceramic substrates and especially for producing copper-ceramic substrates are known in various versions, as are substrates produced using these processes.
Production of a metal coating required to produce printed conductors, terminals, etc. on a ceramic, for example, on an aluminum oxide ceramic using the so-called "DCB process" (direct copper bond technology) using metal or copper foils or metal or copper sheets which form the metal coating, and which have on their surface sides a layer or coating (fused layer) of a chemical compound of the metal and a reactive gas, preferably oxygen, is known. In this process described for example in U.S. Pat. No. 3,744,120 or in German Patent 2,319,854 this layer or this coating (fused layer) forms a eutectic with a melting point below the melting point of the metal (for example, copper) so that by placing the foil on the ceramic and by heating all the layers they can be joined to one another, by fusing the metal or copper essentially only in the area of the fused layer or oxide layer. This DCB process for example has the following process steps:
oxidation of a copper foil such that a uniform copper oxide layer results; PA1 application of the copper foil to the ceramic layer; PA1 heating of the combination to a process temperature between roughly 1070 and 1075.degree. C., for example to roughly 1071.degree. C.; and PA1 cooling to room temperature.